Solar water heating system has been widely recognized by the society and has been widely used.
A Chinese patent literature CN 103016421A discloses a jet device and a water heater comprising the jet device, wherein the temperature regulating principle for the outlet water is as described below. The water inflow rates of cold water and hot water are adjusted by controlling left and right handles of a valve, and the cold water and hot water at different flow rates are mixed in the jet device to form water for use, which is of different temperatures. In the state of jet, the sucking effect of hot water depends on the pressure of the cold water. Once adjusting the handles to turn down a valve spool for cold water, the proportion of cold water will be reduced directly and the jetting speed of working liquid of cold water will be reduced, which will cause the water pressure of the working liquid in the nozzle of the jet device to be reduced directly, making the sucking effect of hot water unsatisfactory.
Therefore, it is required to provide an adjustable jet device used for adjusting the mixing ratio of cold water and hot water, in order to achieve a function of enhancing jetting pressure and a function of adjusting temperature.
In practice, a telescopic needle is used in an adjustable jet device and is disposed inside a nozzle, in order to adjust the flow rate of cold water (working fluid). For example, a Chinese patent literature CN 102767210A discloses an adjustable jet device with multiple water sources, comprising a jet body, a fluid working chamber disposed inside the jet body, a nozzle disposed on the front end of the fluid working chamber, and a needle disposed inside the fluid working chamber and located on an extension line of the centerline of the nozzle, wherein the needle is provided with a control device disposed on one end thereof and used for controlling the moving distance of the needle, and the needle is able to move in the axial direction of the nozzle under the control of the control device, in order to adjust the jetting flow rate of the nozzle.
For a water heater in such a structure as described above, the jetting flow rate of cold water of the nozzle is adjustable via the needle, while the flow rate of hot water is unadjustable. As a result, there will always have a proportion of hot water mixed in the water outflow, making the temperature of the water outflow unable to be close or equal to the temperature of the cold water. The users will feel the water is relatively hot in summer but have no ways to adjust the temperature of the water, resulting in a waste of hot water.
In view of the problem described above, a Chinese patent literature CN 102086941B discloses a valve for mixing water, comprising a valve body which is provided with a cold water inlet, a hot water inlet and a water outlet thereon, and further comprising a nozzle communicated with the cold water inlet and provided with a needle valve used for helping to adjust the flow rate of cold water, wherein the flow rate of hot water is adjustable by screwing the nozzle into or out of the valve body, and the flow rate of cold water is adjustable via adjusting the cross section of the water outlet by screwing the needle valve in or out.
A water heater comprising the valve for mixing water as described in CN 102086941B has the function of adjusting flow rates of cold and hot water. However, it still has some disadvantages as used in practice. Firstly, as the nozzle is rotated to adjust the flow rate of hot water, the needle valve will move along with the nozzle, and will be relatively stationary to the cold water outlet of the nozzle, so the jetting effect of the nozzle will be substantively constant as the flow rate of the hot water is changed, and thus it is unable to meet different bathing requirements from users. Secondly, although the flow rate of the cold water is adjustable via the needle valve, two handles are needed to adjust the nozzle and the needle respectively, and as used by users, the two handles are needed to be adjusted repeatedly and alternately by the users, in order to reach a comfortable bathing temperature, making the use inconvenient. Finally, as the position of the cold water inlet of the nozzle relative to the cold water inlet of the valve body is adjusted by axially rotating the nozzle to control the flow rate of cold water, the flow rate of cold water will be affected and the pressure inside the nozzle will be reduced, which will affect the jetting effect. Therefore, the needle valve has to be used to adjust the flow rate and temperature of the water outflow.